Various means have been used in the prior art to increase the muzzle velocity for ammunition fired in recoilless rifles. Prior art propellant charges for recoilless gun systems used propellant grains which were fabricated in short lengths of round propellant material perforated to obtain a desired web thickness. These prior art charge assemblies consisted of the required number of grains loaded in a packed-bed arrangement having random orientation and unsupported except for adjacent grain surfaces. Due to this random orientation of the grains, simultaneous ignition on all surfaces is impossible to achieve when the charge is initiated and results in a delay of burning on surfaces not ignited initially. Since extremely short burning cycles are required for recoilless rifle propellant designs, this delay results in unburnt portions of the propellant grain being ejected from the system in the nozzle exhaust. Ejection of unburnt propellant material represents loss of energy, thus reducing overall system efficiency and causing conditions which result in non-uniform interior and exterior ballistics performance. These problems in prior art propellant grain materials cause inaccuracy in present recoilless rifle systems.
One of the prior art means for solving the aforementioned problems was to include a trapping arrangement in the system hardware which limited material size in the gas exhaust or otherwise delayed ejection of unburnt propellant materials. Another prior art means used to increase system efficiency was to have the cartridge case perforated with large numbers of holes to port the gas into the chamber around the outside of the case before it could be exhausted through the nozzle. The trapping arrangement has been an unsatisfactory solution because it had only limited success in increasing the efficiencies of recoilless gun systems. The trapping arrangement requires additional charge weight to be included in the system. In addition, non-uniform ignition is not eliminated and the propellant is still unsupported during combustion. Also hardware components required for the prior art systems generally require complicated and hence costly fabrication methods and increased system weight.